Radar-estimated rain totals of 13 to 15 inches had been observed along the Matagorda coast near Freeport, where Imelda — the super-soaked depression spurring the inundations — made landfall Tuesday afternoon.
With little storm motion expected within the next 24 hours, Houston could start to see some of the persistent, heavy rain bands on Wednesday. A widespread 2 to 5 inches, with localized 7-inch amounts, is possible within the city and northwest, though that could change, particularly in southeastern parts of the city.
Radar on Wednesday morning showed the northern edge of the heavy precipitation shield backing into Houston. Moderate to heavy rainfall is likely in the city of 2.3 million by noon.
From just east of Matagorda Bay, 60 miles southwest of Galveston, up through Port Arthur, 90 miles east of Houston, a band of 10 mile-high thunderstorms continues to drop rainfall at ridiculous rates, briefly spiking to nearly half a foot per hour. A gauge within that band in Bay City recorded 3.88 inches of rain in one hour.
Doppler radar estimates a total of nearly two feet over the San Bernard National Wildlife Refuge. Within the band, a general 10 to 18 inches, with isolated 2-foot amounts, can’t be ruled out. The most likely spot for this would be near the Brazoria/Matagorda County line.
Data suggests this band will largely remain the focus of the heaviest rainfall from this system through Wednesday afternoon, drifting slightly east throughout the course of the day. That may shift the focus away from the Lake Jackson area to the Palacios corridor in Texas this evening, while heightening the flood risk on the east side of the band near the Texas/Louisiana region.
If this scenario comes to pass, the Beaumont and Port Arthur region may become a hot spot for flooding Wednesday afternoon into early evening.
It then looks as though any holes in the radar now over Houston may start to fill in overnight into Thursday morning. Although Houston may not end up with the highest rainfall totals, dangerous flooding is possible if any rain bands target the vulnerable, concrete-blanketed city. Some models indicate the possibility of this occurring. The flood risk for Houston will increase Wednesday afternoon and remain into early Thursday morning.
